Field
Embodiments described herein generally relate to the gasification of hydrocarbons. More particularly, such embodiments relate to cooling particulates recovered from a gasification process.
Description of the Related Art
Raw synthesis gas leaving a gasifier can contain particulates such as coarse ash, fine ash, and/or slag that need to be removed prior to further processing. The bulk of the particulates can be removed using a particulate removal system such as filters and/or cyclones. The removed particulates are typically recycled to the gasifier or purged from the system as a byproduct, and the syngas leaving the particulate removal system is further processed and/or purified. The removed particulates, however, typically require cooling before being recycled or purged from the system.
One method for cooling the removed particulates is to drop the hot particulates into a vessel of water and the cooled particulates are then separated from the “dirty” water. This method is not very efficient and only works at low pressures. Another method is to feed the hot particulates to a large horizontally oriented, fluidized bed having cooling coils disposed therein. A large fluidized bed, however, is not easily expanded or contracted to meet the typical cooling requirements of the system. It can also require high energy input to keep particulates flowing through the fluidized bed. And if a portion of the fluidized bed malfunctions, the entire gasification process might have to slow or come to a halt until the fluidized bed cooler can be repaired. Yet another method is to feed the hot particulates to a vessel containing coiled cooling tubes. These tubes, however, can succumb to the thermal stresses caused by the high temperatures of the hot particulates. Also tube expansion or contraction can exist when particulate temperature changes due to varying heat load. The tube expansion or contraction can lead to thermal stress causing cracks or other damage to the cooling tubes, which could require a halt to the entire gasification process to repair the cooler.
There is a need, therefore, for new apparatus, systems, and methods for cooling particulates recovered from a gasification process.